Improvement in air-engines



J. R. NAPIER 8v W. J. M. RANKINE.

AIR ENGINE.

No. 11.696. Patented Sept. 19, 1854.

UNITED STATES PATENT OFFICE.

JAMES R. NAPIER, ()l GLASGKNV, AND \VILLIAM J M. RANKINE, OF GOVAN, SCOTLAND.

IMPROVEMENT IN AIR-ENGINES.

Specification forming part of Letters Patent No. 1 [,696, dated September 19, 1854.

Queen of Great Britain, have invented or discovered new and useful Improvements inEngines for Developing Mechanical Power by the Action of lleat on Air and other Elastic Fluids; and we, the said JAMES ROBERT NA- PIER and '\\"ILLIAM JOHN MAcouoRN RAN- KINE, do hereby declare the nature of our said invention and in what. manner the same is to be performed to be particularly described and ascertained in and by the following statementsthat is to say:

place at a higher temperature and the condensat-ion at a lower temperature, and which are known by the names of air-engines and caloric enginesl The engine which we. will now describe for the purpose of showing the nature of the improvements proposed by us,and which is represented in the annexed drawings, forming part of this specification, consists partly of parts and combinations of parts which have been heretofore used and partly of parts and combinations of parts which we claim as our invention for the improvement of such engines, and which we shall hereinafter specify and claim in detail.

The arrangement of the different portions of the engine shown in the drawings is one of many practicable arrangements which we select as being well adapted to display all the essential parts of the engine at one view. It is obvious that the essential parts of the engine being properly connect-ed with each other may be. arranged in any other way which may be found best suited to the situation in which it is to be used and the work which it is to perform. The frame-work by which the working parts of the engine are to be supported is omitted from the drawings, because it involves nothing new or peculiar and would interfere with the distinct representation of the working parts.

Figure 1 represents averticai section of the engine. Figs. 2, 3, i, and 5 are plans of detached portions to be afterward more particularly specified.

In Fig. 1, A is a vertical section of a-cylinder containing a piston B, which is coni nected by means of a connecting-rod D. with a crank'E and gives motion-to a shaftF,

which may be used to drive any machinery and on which is a fly-wheel. (Not shown in the drawings.) Besides the mode. here shown of connecting the piston with the crank, any of the'other modes used in steanrengines an air-engines might be employed.

H is a passage connecting the cylinder with a strong air-tight receiver K, th-ebody or central part of which is cylindrical,-and is shown in section in Fig. 1. The uppermost part of this receiver consists of a number of tubes of brass or other suitable metal open at thebottom, where they arejstrongly fixed in a plate j. These tubes are to be surrounded by water circulating in a tank C). Their arrangement is shown in the plamFig i. Three of these tubes (marked 1) are provided with stu it ing-boxes at the top, being intended for the passage of rods to be afterward described. The remainder (marked i) are closed at the top, and it is intended that the air or other gas should be cooled in them,

The lowest part of the receiver K consists of a number of tubes-of brass or other suit-,

able metal (marked is) arranged in the manner shown in the plan, Fig. 3, closed at the bottom and open at the top, where they are strongly fixed in a plate 1 It is intended that the air or other gas should receive heat through them by conduction from the flame of a furnace circulating in a flue L around and between the tubes. The plate L is pro-' tected from-the action of the flame by a fireclay shield o.

M is a fine conducting the flame from a [urnace; N, ailuc which conducts the products of combustiop to the chimney.-

P is a plunger, of sheet iron or other metal, divided into compartments so as to be at once light and strong, as shown in the plan, Fig. 4:. Some of these compartments are to be air-tight and to be filled with brick-dust, fire-clay, or some other substance which conducts heat slowly; but. one or more compartments are to extend through the plunger, so as to form a passage for air or gas, and are to be filled with a series of layers of wire-gauze or thin. perforated metal plates, strips, or wires, or of some substance capable of conducting heat rapidly, and so formed and arranged as to expose a large surface for the communication of heat to and from the air which may pass through. One such passage occupied as described is represented by p in the section and plan.

The plunger 1 is to be made to fit the body of the receiver K as closely as is consistent with its moving up and down with as little. friction as may be against the sides of the receiver. his to be suspended by one or more rods from levers (marked R) which move on a pivot 9' and have a countcrpoise at V. In the engine shown in the. drawings there are two such rods for this plunger, (marked Q.) They work through stufting-boxes at the top of two of the tubes I and are attached toa cross-bar, which ishnng from the levers R by a pair of links J,and is so formed as to allow a third rod '1 to pass freely through it for a purpose to be afterward stated. Another of the tubes I is traversed by this rod. The tubes i, two of which only are shown in sec- -tion, are occupied by cylindrical rod-shaped metal plungers g, which, being arranged as shown in the plan, Fig. 4, are fixed to the top of the plunger P, forming part of it and moving along with it and fitting the tubes '11 loosely, so as to leave a passage for air or gas all round each tube about an eighth of an inch wide. The rod T, suspended from the beam U,

works through a St oiling-box at the top of one of the tubes I, and, descending through that tube, averses also the center of the plunger? by a passage wide enough to letit work without friction, and is attached to the heat-screen S. This heat-screen consistsof a circular plate. 8, of iron, brass, or other suitable metal, pierced with holes fitting the cylindrical part of the receiver K, but not so' tight as to produce friction, and'of a series of rod-shaped plungers t, of brass, copper, or othersuit-able metal, fixed to this plate and. moving with it' and capable of filling the tubes 70, except a passage of about an eighth of an inch all round each tube. This heat-screen is shown in plan in Fig. 5, where the holes in the plate 8 are indicated by small full circles, the rod-shaped plungers t by dotted circles, and the rodT by which the heat-screen is suspended, by a dark spot.

The object of the heat-screen is to-rcgulato the transmission .of heat from the flame in the chamber L to the air or other gas in the lowerpart of the receiver K, so that it shall take place wholly or chiefly during the expansion of this air or other gas, which is the period most favorable for the development of mechanical power, and shall be, wholly or almost wholly cut off at other times when the heat would be'wasted or would impede the action of the engine. The rodsq and t may be made hollow for the sake of lightness, but the hollows should be air-tight.

The forrn'of the. heat-screen shown in the drawings is a result of the tuhularform of the bottom of the receiver with which it is made to correspond. Should the bottom of the receiver be made of any other shape, the heatscreen must be made to fit it. Inlike manner the top of the plunger P is to be made to fit the top of the receiver. The beam U, from which the heat-screen hangs by the rod T, moves on the axis 21.

V'is a counterpoise to balance wholly or partially the weight of the heat-screen.- In stationary engines a preponderance may be allowed to the heat-screen sufficient to make it descend to the bottom of the receiver from produced by means of a spring or some other suitable mechanical contr1vance.-'-

The cam X is so formed that while the air is being compressed or being cooled-the.

heat-screen S remains quiescent atthe bottom of the receiver K, and while the air is expanding and receiving heat the heat-screen rises and falls. Other mechanical contrivances might be used to produce the. same motion of the heat-screen.

D cl is a handle for raising the heat-screen by hand.

Y is an eccentric-wheel forworking the plunger P. By means of the rod Z it gives a reciprocating motion to the levers R.

E e is a rod for working forcing-pump F f, by which air orthe other gas employed is to be compressed into the receiver and cylinder, both to obtain a suificient pressure and to supply the loss by leakage.

H h is an adj Listing-screw by which the rod E e can be lengthened or shortened, so as to increase or diminish or altogether to stop the supply of compressed air or gas forced into the engine at each stroke of the pump.

L l is a valve opening upward leading from the compressing-pump into the receiver and cylinder. v v

M m is a safety-valve.

N n is a 'forcing-pump, w'hich supplies a stream of cold water to the tank 0, which gradually rising among the tubes contained in that tank escapes finally by the waste-pipe 0 0, which should be conducted to some convenientoutlet. In locomotive and marine engines the tanks should be subdivided by their perforated partitions to check agitation of the water. Another mode of cooling the tubes is to sprinkle them with water from a number of jets.

Q q isa prcssuregage. It should be capable ot' indicating pressures up to two hundred pounds on the square inch. 7

P p is an outer casingi'or the lower part of the cylindrical body of the receiver K, filled with brick-dust, engine-ashes, or some other siow conductor of heat.

R r are dampers for the fines. 1n the engine shown in the drawings the receivers are vertical; butit is obvious that they might be placed horizontally, the plungers and heatscreens being supported on rollers and the motion of the heat-screens toward the hot sides of the receivers being produced by springs or other mechanical contrivances.

Having thus described the parts of the engine and their connection with each other, we shall now describe how it is to work. During the working of the engine the following is thesuccession of changes undergone bythe air in the receiver K: During the downstroke of the piston the heatsereen lies at the bot-' tom of the receiver. The plunger P descends and the air,'with the exception of a trifling quantity, passes through the passage pand gives out a large portion of its sensible heat V to the wires,strips, or sheets of metal or other conducting-bodies contained in that. passage,

The remainder of the excess of the heat 'of the air above that of the Water in the tank 0 is abstract-ed by the surface of the tubes i and rods q. The downstroke of the piston causes this air to be compressed. This compression produces heat, which is also abstracted by these rods and tubes. This heat were it not so abstracted would increase the elasticity of the air and oppose the motion of the piston. DuringtheupstroketheplungerPrises,theair descends through the passage 1) and recovers the greater part; of the sensible heat formerly lost from the wires or metal sheets or strips or other conducting substances, the heatscreen S is raised and dropped, and the air by circulating over its rods If and through the hot tubes 71 acquires the remainder of the sensible heat necessary to elevate its temperature and also the latent heat necessary. to expand it. This completes the cycle of operations. 1 The effect of these operations is of a similar nature to that which takes place in ,all engine's driven bythe action of heaton an elasticsubstanceiwia, that the substance is alternately expanded at a higher temperature and contracted at a lower, so that the power developed by the expansion is greater than the power consumed by the contraction, and

a surplus of power remains to drive inachinery.

\Vhen the engine begins to work, should the cylinder and receivers be filled with air or other gas at a pressure not sufiiciently great to perform the required work, the engine must be disconnected from the machinery it is intended to d ive, and the pump-rods h] e-being adjusted by the screw [l 71, so that the piston of the pump shall nearly touch the bottom of the barrelat each stroke, the whole surplus power of the engine will be employed for some minutes in filling the receiver and the cylinder with compressed air. 'hen the gage indicates that the required pressure has been attained, the engine may be connected with the machinery to be driven and the pump-rod Eeshortened by means of the screw II It, so as to supply enough of air only to make up for leakage, which condition will be indicated by the pressure-gage.

The engine shown in the drawings is a single-acting engine, being the most simple form, steadiness of motion being obtained by means of the inertia of a fly-wheel and by properly adjusting the weight of the piston B.

Thcsteadiness of motionfmay be increased, as in the case ofsteam-engines, by using a double-acting engine having a receiver connected with each end of the cylinder, or by using-two or more engines to drive the same shaft, their motion being so-adjusted as to produce the nearest'possible approach to uni formit-yof action onthe shaft. It is evident that many ofthedetails may bevaried without-departing from the peculiar character of our invention as herein described. Having thus described the nature of our invention, we would have it understood that we make no claim toiany of the mechanical parts separately; but i Te claim as the improvements which constitute thepeculiarity of the engine- I 1. The invention and adaptation of what we havecalled a heat-screen, the form of which may be Varied, and the means of giving motion thereto may also be varied, the

I said heat-screen being separate and distinct from the plunger which drives the air or otherv gas from the hot to the cold end of the receiver, and. vice versa, and being adapted to the following purposes: first, to screen the principal portions of the airor other gas from the communication of heat from the furnace or source of heat at those times when that heat would impede the motion of the engine that is to say, when the air or other gas is being passed toward the cold. end of the receiver to be cooled, when it is not being expanded, and when it is being compressed; second, to receive and store up inits own material at such times the heat communicated from the furnace; third, to permit and accelerate the communication of heat to the air or other gas at the time when it is most offeetive in developing mechanical powerthat is to say, When the air or other gas is being expanded- 2. The adaptation of tubular receivers for the purpose of heating and cooling the air or other gas in the'manner described in this specification-that is to say, by the aid of rod-' shaped heat-screens or plungers nearly filling the tubes and serving by being moved out and in, whetherby the mechanism shown in the drawings or by any other suitable mechanism, to admit and expel the air or other gas and promote its circulation over the heated or cooled surface.

3. We do not, however, claim the invention of tubes as a means of increasing heat-conducting surface, but simply the adaptation'of tubes to engines worked by the actionof heat on air or other gas by the aid of the rod-shaped heat-screens or plungers before described.

W. J. MAooUoRN RANKINE. 

